Final answer:
All the given statements about RNA are true; it contains ribose sugar, adenine, and is composed of nucleotides. RNA differs from DNA in the sugar it contains and the base pairing involving uracil instead of thymine.
Step-by-step explanation:
The student asked which of the following is not true of RNA:
- It contains ribose sugar.
- It contains adenine.
- It is composed of smaller molecules called nucleotides.
- All of the above are true of RNA.
The correct answer to this question is: d. all of the above are true of RNA. RNA does indeed contain ribose sugar, which differentiates it from DNA which contains deoxyribose. The sugar present in RNA nucleotides does contain a hydroxyl group at the 2' carbon, compared to the missing oxygen in the deoxyribose of DNA nucleotides. RNA also contains the nucleobase adenine, but instead of pairing with thymine as it does in DNA, it pairs with uracil in RNA. Lastly, RNA is indeed made of nucleotides, each consisting of a nitrogenous base, the five-carbon sugar ribose, and a phosphate group. RNA is often single-stranded, which is a stark contrast to DNA's double-stranded helical structure.